Symptoms

Submitting a request from service portal throws errors like 'Evaluator: java.lang.NullPointerException' with possibly failing widgets like Ticket conversation and errors/messages in log similar to 'com.glide.glideobject.GlideDateTime.addSeconds(GlideDateTime.java:1172)'  and 'SEVERE *** ERROR ***performing addSeconds with invalid GlideDateTime' 

Release

Any release supporting Service Portal

Cause

In most cases there was a customized business rule referencing DateTime type fields and causing issue

Resolution

The issue was due to a customized business rule which got resolved after customer deactivated the business rule or fixed the script where the datetime field was referenced. A hint to find which business rule is causing the problem maybe to check the Updated field for any recent updates.